1. Technical Field
The present invention relates to an optical type of movement amount detection device for measuring the amount of movement of a printing medium in non-contact fashion, and to an error information production method.
2. Related Art
With a conventional printing device that performs printing while conveying a printing medium, the printing medium in contact with a roller is conveyed by the rotation of the roller. How much the printing medium has been conveyed can be ascertained from the amount of rotation of the roller and the roller diameter, but if the roller wears down and slippage occurs between the printing medium and the roller, this will result in error. Accordingly, in addition to a method for detecting the amount of movement of a printing medium from a roller that conveys said printing medium through direct contact, there is a known method in which the amount of movement of a printing medium is detected by illuminating the surface of a printing medium being conveyed by a roller, acquiring a plurality of images of the surface of this medium, and comparing these images (see, for example, Japanese Laid-Open Patent Application Publication No. H6-56314).